Supplies of clean gasses are often needed in laboratories, research facilities, etc. Cylinder gas is often used for supplying clean gas, but such arrangement provides only a finite amount of clean gas and the cylinders can be expensive to refill and/or replace. Gas cylinders also can be a safety hazard.
Another option for supplying clean gas is to utilize one or more gas purifiers for generating desired purified gas streams onsite. For example, hydrogen purifiers are often used for provided a purified stream of hydrogen gas. A known type of hydrogen purifier has a gas-tight chamber in which is provided a coil of tubing of palladium alloy. The coil has at one end an externally accessible input end and at the other end of the coil an externally accessible output end. Crude hydrogen carrying impurities is fed under pressure into the input end and a waste gas containing all of the impurities is withdrawn from the output end of the coil. When the coil is heated to a sufficient temperature, hydrogen permeates through the palladium-alloy wall of the coil and can be withdrawn from the interior of the chamber. Such a filter is termed an absolute filter as nothing but hydrogen can pass through the walls of the tubing, so that hydrogen of perfect purity can be withdrawn from the chamber.